One regret I have about ActivityPub is that navigating reverse chronological collections is really error-prone. "first", "last", "next" and "prev" mean the opposite of what you think they mean, so it's easy to get mixed up and navigate things the wrong way.
It's too late to change now, but I could see adding some synonyms for these properties, like "newest", "oldest", "older" and "newer", to make it easier to do the navigation code.